<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>   
    <script src="https://unpkg.com/vue@3/dist/vue.global.js"></script>
    <link href="./css/jisuan.css" rel="stylesheet">

</head>
<body>
    <div id="app">
        <div class="my">
            <input type="text" v-model:value = "counter" class="cin_item">
        </div>
        <div class="content">
       <button class="item" @click="counter +=0">0</button>
       <button class="item" @click="counter +=1">1</button>
       <button class="item" @click="counter +=2">2</button>
       <button class="item" @click="counter +=3">3</button>
       <button class="item" @click="counter +=4">4</button><br>
       <button class="item" @click="counter +=5">5</button>
       <button class="item" @click="counter +=6">6</button>
       <button class="item" @click="counter +=7">7</button>
       <button class="item" @click="counter +=8">8</button>
       <button class="item" @click="counter +=9">9</button>
       </div>
      </div>
    </div>  
</body>
<script>
    const counter = {
        data(){
            return{
                counter: 0
            }
        }
    }
    Vue.createApp(counter).mount("#app")
</script>

</html>